A turbine engine fan comprises a disk carrying blades having roots engaged in substantially axial slots formed in the outer periphery of the disk. The blades are held radially on the disk by co-operation between the shapes of their roots and the shapes of the slots in the disk, the blade roots being of the dovetail type, for example. Inter-blade platforms are mounted on the disk between the fan blades.
A fan of that type is described in document FR 2 930 595 in the name of the Applicant, and in that document the annular disk does not have balance weights or balance hub, but comprises a rim having upstream and downstream radial faces into which the mounting slots for the blade roots open out. A cylindrical lip extends axially from the upstream radial face of the rim and a groove is formed in the lip upstream from the blades for the purpose of mounting means for retaining the blade roots axially.
The blades are also held axially in the downstream direction by bearing against an annular cheek plate that is fitted onto the downstream end of the rim and that is fastened thereto by bolting, which cheek plate includes an inner annular flange for fastening to the upstream end of a shaft of the turbine engine.
The inside surface of the disk includes a cylindrical portion connected upstream to a larger-diameter portion forming a setback situated downstream from the upstream radial face of the rim.
In operation the radial forces generated by the rotating fan blades generate tangential stresses in the disk in its portion presenting the slots for mounting the blade roots. In addition, bending stresses are created by the above-mentioned lip, in particular in the zone of the setback.
Thus, in that zone, the tangential stresses and the bending stresses are cumulative, thereby leading to risks of the disk breaking or becoming degraded.